Remote sensing techniques are increasingly utilized in many fields including gas detection. More specifically, numerous chemical species detection techniques isolate and identify chemical species by exploiting unique spectral features. Many of these techniques use optical filters or include components that may be replaced by optical filters.
Some optical filter based remote sensing systems use a single focal plane array (FPA) with a rotating disk in front of the FPA that has multiple optical filters. To obtain a multi-spectral data set, one image is taken with each filter in the imaging path, while the filter wheel is rotated between imaging shots. This cumbersome approach is not acceptable in modern color photography and need not be acceptable in remote sensing situations.
Digital color photography is most commonly accomplished by using a Bayer filter superimposed on a focal plane array. The Bayer filter is an optical filtering array that includes three types of elements transmitting red, green, and blue light toward the FPA. The Bayer filter is placed in front of the FPA and aligned with the pixels of the FPA, such that each pixel may receive a filtered light transmitted through the Bayer filter.
As will be explained, remote sensing of a gas is accomplished by the present invention by using a filter mosaic that is registered, or aligned with the pixels of an FPA. Through proper alignment of the filter mosaic with the pixels of the FPA by the present invention, light arriving from a plume of the gas is filtered, detected and identified.